This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A003439 M5474 #30 Apr 09 2020 22:26:11
%S A003439 1,720,202410,20933840,1047649905,30767936616,602351808741,
%T A003439 8575979362560,94459713879600,842286559093240,6292583664553881,
%U A003439 40447642842118656,228438173705550566,1152877640765297760,5271278793334883190,22085628572718605376,85604721304213863531
%N A003439 Number of 6 X 6 stochastic matrices of integers: all rows and columns sum to n.
%D A003439 Matthias Beck and Dennis Pixton, The Ehrhart Polynomial of the Birkhoff Polytope, Discrete & Computational Geometry, 30(4)(2003), 623-637.
%D A003439 D. M. Jackson and G. H. J. van Rees, The enumeration of generalized double stochastic nonnegative integer square matrices, SIAM J. Comput., 4 (1975), 474-477.
%D A003439 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A003439 Alois P. Heinz, <a href="/A003439/b003439.txt">Table of n, a(n) for n = 0..1000</a>
%H A003439 D. M. Jackson & G. H. J. van Rees, <a href="/A002817/a002817.pdf">The enumeration of generalized double stochastic nonnegative integer square matrices</a>, SIAM J. Comput., 4.4 (1975), 474-477. (Annotated scanned copy)
%H A003439 Dennis Pixton, <a href="http://www.math.binghamton.edu/dennis/Birkhoff/polynomials.html">Ehrhart polynomials for n = 1, ..., 9</a>
%H A003439 M. L. Stein and P. R. Stein, <a href="/A001496/a001496.pdf">Enumeration of Stochastic Matrices with Integer Elements</a>, Report LA-4434, Los Alamos Scientific Laboratory of the University of California, Los Alamos, NM, Jun 1970. [Annotated scanned copy]
%F A003439 a(n) = Sum_{j=0..10} A005467(j) * binomial(5+j+n, 5+2*j). - _Andrew Howroyd_, Apr 09 2020
%Y A003439 Row n=6 of A257493.
%Y A003439 Cf. A005467.
%K A003439 nonn
%O A003439 0,2
%A A003439 _N. J. A. Sloane_
%E A003439 More terms from Melissa Erdmann (merdmann(AT)nebrwesleyan.edu), May 07 2009
%E A003439 Offset changed to 0 by _Alois P. Heinz_, Apr 26 2015
%E A003439 Name clarified by _Charles R Greathouse IV_, Mar 03 2018